Braves WPA

Get straight to the stats: 2008 Braves WPA Statistics

Introduction

Let me begin by explaining some of the unique stats you’ll see here.  I’ll work on getting a full glossary together, but this should take care of some of the weird stuff you might not be used to seeing.

WPA Basics

WPA – Win Probability Added – Simply put, a player either adds or subtracts from his team’s probability of winning the game based on his actions on the field. WPA measures that change in probability based on tables derived from historical results and some higher math.

LI/Leverage – The average game situation has a leverage rating of 1, so “more important” situations have leverage greater than 1, and “less important” situations are less than 1. Tom Tango should be credited for the math behind this number.

WPA/LI – WPA is great, but it’s hugely dependent on game context. High-leverage situations generate larger changes in WPA, so this number neutralizes that effect. You could call it leverage-neutral or context-neutral WPA, and it’s probably a better indicator of overall ability within the WPA framework.

Clutch – This is what FanGraphs calls clutch, at least, and it’s calculated as simply [Clutch = WPA - WPA/LI]. Even though it subtracts WPA/LI, “Clutch” is still somewhat dependent on the leverage a player faces, so I break it down further into “EC,” which is the leverage-dependent portion of “clutch” and “CP,” which is actual clutch performance.

Other Random Stuff

Anything starting with “p” is that number divided by plate appearances, so you’ll see lots of WPA rate stats with that prefix.

QS* – Quality Start – My definition, rather than 6 IP and 3 or fewer runs allowed, is 6 IP and a positive WPA.

I like to use David Smyth’s BaseRuns (BsR) as a run production estimator, since it models the game in theory better than Bill James’ Runs Created (RC) formula. For hitters, I include both.